Patients that suffer from stroke, cardiac arrest, or head trauma, as well as patients that have undergone invasive brain or vascular surgery, are at risk for ischemic injury which can occur when an organ does not receive a sufficient supply of oxygen. For example, in the case where a patient suffers from a stroke, a clot blocks the blood supply to a portion of the patient's brain. As a result, the patient can experience a critical rise in intra-cranial pressure, brain cell death, and a loss of brain function.
To help minimize ischemic injury after such a traumatic event, systemic hypothermia can be induced in the patient. The effectiveness of systemic hypothermia therapy is a function of several factors including, for example, the level of cooling of the patient (between temperatures of approximately 30° C. and 35° C.), the amount of time that elapses between an original insult, such as cardiac arrest or heart attack, and achievement of protective levels of hypothermia, and the duration of the hypothermic state.
Systemic hypothermia has historically been applied to a patient by immersion of the patient's body in a cool bath where the depth and duration of hypothermia is limited by the patient's ability to tolerate the therapy. Currently, there are several conventional systemic hypothermia systems available. Such conventional systems include pads having fluid circulation channels disposed within the inner walls of the pads. The pads can be applied to a patient's body and cooled water can be circulated through the pads to cause a thermal exchange between the patient and the pad to induce systemic hypothermia in the patient.
Attempts have also been made to induce hypothermia in a patient by local cooling the surface of the patient's head. For example, certain head-cooling devices include a head cap with a gel-filled liner. Prior to use, the head cap is placed into a freezer to reduce the temperature of the gel. During use, the cap can be placed on the head of a patient such that thermal exchange occurs between the chilled liner and the patient's head to locally induce hypothermia in the head of the patient. However, the presence of hair and/or air pockets between the scalp of the patient and the liner walls can act as a thermal insulator and can minimize the effectiveness of the heat transfer between the patient's scalp and the cap.
There is a need for improved hypothermia devices that provide direct contact between a cooling fluid and a patient's scalp to induce local hypothermia within a patient.